1. Field of Invention
The present invention relates to a light source having a lamp, such as a high-pressure mercury lamp or a metal halide lamp, and a projector provided with this light source.
2. Description of Related Art
A related art projector includes an illuminating optical system having a light source which emits an illumination light, an electro-optic modulator which modulates the illumination light from this illuminating optical system according to image signals, and a projecting optical system which projects and displays the light modulated by this electro-optic modulator as a display image on a screen.
For such a projector, it is required that the projected image (display image) be light, the luminous intensity of the illumination light be high, and the color balance be good.
Therefore, in order to obtain a higher luminous intensity, a related art illuminating optical system is often provided with a light source having a high-pressure mercury lamp combined with a concave mirror (reflector).
Instead, in order to obtain better color balance, there is the other related art illuminating optical system provided with a light source having a metal halide lamp.
In the light source of these kinds of illuminating optical systems, a luminous tube (vitreous silica tube) of the lamp may burst due to the increase of vapor pressure during lighting. Therefore, the lamp is arranged in a sealed space (reflector in which an opening part is covered with a transparent glass plate) to prevent scattering of the broken pieces of the lamp to the outside caused by a burst of the luminous tube.
However, in such a structure (sealed structure), heat generation of the lamp makes the temperature inside the sealed space high. As a result, the lamp enters the excessively heated state, which shortens the life of the lamp.
Therefore, in order to reduce or prevent the scattering of the broken pieces of the lamp to the outside, and to lengthen the life of the lamp, a light source is disclosed in JP-A-10-254061, in which a permeable port is provided in a defined wall (reflector etc.) in which the lamp is housed, and a mesh covering this permeable port is attached.